Improvement in processes of hardening steel



UNITED STATES A'IENT OFFICE.

SAMUEL W. ETOHELL, OF WEATHERLY, AssIeNoE TO HIMSELF, 1). L. EATON, 0EsAME PLAcE, AND ANNIE E. ALLEN, 0E PHILADELPHIA, PA.

IMPROVEMENT IN PROCESSES OF HARDENING STEEL.

Specification forming part of Letters Patent No. 134,872, dated January14, 1873.

To all whom it may concern:

Be it known that I, SAMUEL W. ETCHELL, of Weatherly, Carbon county,Pennsylvania,

have invented a Process of Hardening Steel,

of which the following is a specification:

The object of my invention is to make steel intensely hard withoutrendering it brittle; andthis object I attain by treating it with boraxor caustic alkali, or their equivalents, and mercury, in the mannerwhich I will now proceed to describe.

I heat the tool or other object of steel until it is of a bright redcolor, and then roll the portion to be hardened in pulverized borax, orI apply the latter to the heated steel in any other convenient manner,after which the steel may be again heated, and the operation may berepeated several times, although in most cases one application of theborax will suflice. After this treatment, and while the steel is redhot, I plunge as much of it as is required to be hardened into a bath ofmercury, which renders the steel intensely hard without imparting to itthe brittle character which results from plunging heated steel intowater.

A preparatory treatment of the hot steel with caustic alkali will renderthe steel somewhat harder than the borax treatment. Other alkalinesubstances may be employed for the preparatory process in place of boraxor caustic alkali; but I have found the latter to be particularlyeffective, so much so that by its aid and by the mercury bath, I haverendered drilling-tools hard enough to bore holes through ordinaryfiles.

I claim as my invention- The process of hardening steel by treating thesame with borax, or its equivalent, and mercury, as set forth.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

SAMUEL W. ETOHELL.

\Vitnesses:

J. PATTON MooRE, J OHN F. DAVIs.

